It is known to require the extraction of sample quanta from pipelines and other process flow operations. Such sampling is required in many types of operations, including oil and gas processing, mineral processing, chemical processing, food preparation and pharmaceutical preparation.
A known type of sampling device is bolted to the side of a pipeline, and comprises a rod which slides through a cylindrical tube aligned radially to the pipeline. The rod includes two sets of axially separated circumferential seals which engage with inner walls of the tube, and a sample spool piece located between the two sets of seals. In order to acquire a sample, an end of the rod including an outer circumferential seal set and the sample spool piece are moved axially from the tube into the pipeline. Product from within the pipeline thus flows about the sample spool piece, up to the second, inner circumferential seal set. The rod is then withdrawn into the tube, with a sample being held in the sample spool piece between the two seals. The rod is withdrawn a sufficient distance that the inner seal passes over an aperture, through which the sample is extracted for testing.
There are several drawbacks to use of such a device. Principal amongst these is that the outer circumferential seal set slides within the tube, and is thus subject to wear. During normal product flow within the pipeline, when sampling is not occurring, this outer seal set is required to prevent leakage from the pipeline. As such, should wear occur, the pipeline must be shut down and emptied in order for the seal set to be replaced.
The present invention attempts to overcome at least in part some of the aforementioned disadvantages of previous sampling devices.